People with PNH may also have underlying problems with the function of their bone marrow (such as aplastic anaemia and myelodysplastic syndromes), which reduce the production of blood cells and may further complicate PNH.  Every case of PNH is unique, and signs and symptoms can vary widely in their frequency and severity from person to person.

The most common signs and symptoms of PNH include:

• Blood clots (thromboses)
• Kidney problems
• Pain (usually in the back of the abdomen, but can also occur in the head or back)
• Difficulty breathing (dyspnoea)
• Erectile dysfunction
• Difficulty swallowing (dysphagia)
• Yellowish-coloured skin or eyes (jaundice)
• Feeling tired (fatigue), which can be disabling
• Reduced levels of red blood cells (anaemia), which may require blood transfusions
• Dark-coloured urine (haemoglobinuria)